sorry i took so long to reply iv only just stumbled over your post..
yeah that problem plagued my graflex hyperblade, its very frustrating to have that reversed thing happen when the sound goes and the blade stays on then you cant do anything but restart it with the kill key and its completely random sometimes its fine for weeks then it happens.. it drove me mad
the sound board resets but the led driver doesnt thats why the sound resets and the blade stays on so the problem is the conection between driver and sound board most probly at the header, (the header is the white block with the pins in it on the sound board that you plug the wire from the driver board in to)
this is what i did to fix it..
i opend up the saber and i noticed that neither board was isolated so thats what i did first using heat shrink wrap then i found that the wires were a bit cramped in ther all tightly pressed together at the header, so i fiddled around a little to try and make a little "breathing space" for the electrics i defo think its something to do with the contacts that press into the header on the sound board, if they are squashed it causes problems.
i dabbed a little petrolium jelly (vasaline) on the contacts to make sure thers always a conection and put it back together and while it does happen now and again its nowhere near as bad as it was (mabey 1 time in every 50 now) usually with a very harsh swing or clash
also to note the 3 pack triangilar battery does sometimes reset the sound board it even says on hypers site to not use that battery with the saber sd as it causes the sound board to freeze/restart... are you using that battery?
if you know what your doing have ago yourself if you dont have a clue with this sort of thing get a sabersmith.. do-clo is a certified hyperblade smith
it is however a pretty simple set up its just 2 boards plugged together and wire to a led strip, switch and battery, placement of the boards is key
hope it gets sorted cos its one lovely saber and i was very interested in buying it, if ever you decide to sell it if the time is right i may be interested